<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>my css1</title>
    <link rel="stylesheet" href="mycss3.css">
</head>
<body>
<a href="#">这是一个超链接</a>
<hr>
<h1>Hello World!</h1>
<hr>
<h2>Hello World!</h2>
<div class="g1">div1</div>
<div>div2</div>
<div class="g1" id="div3">div3</div>
<p class="c1">P 你好</p>
<div class="c1">div 你好</div>
</body>
</html>